1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device which includes a wet etching step for removing reaction products of dry etching from a semiconductor wafer or simultaneously removing reaction products together with a resist mask.
2. Background Art
For example, Japanese Patent Application Laid-Open No. 49-10746 discloses a conventional technique of cleaning a silicon wafer with a mixed liquid of sulfuric acid, a hydrogen peroxide solution, and hydrofluoric acid. However, this publication does not disclose any technique for removing reaction products of dry etching and a resist mask.
For example, Japanese Patent Application Laid-Open Nos. 4-142741 (publication (1)), 7-99178 (publication (2)), and 8-339996 (publication (3)) disclose techniques of removing a resist mask and reaction products produced by dry etching of a silicon oxide film or a polysilicon film on a silicon substrate. Specifically, publication (1) relates to a technique of removing adherent particles, publication (2) relates to a technique of removing a layer that has been damaged by dry etching, and publication (3) relates to a technique of removing minute foreign substances by wet etching. That is, publication (1) discloses a wet etching technique that uses, in turn, sulfuric acid/hydrogen peroxide solution, pure water, hydrogen peroxide solution/aqueous ammonia, and pure water. Publication (2) discloses a wet etching technique that uses, in turn, hydrofluoric acid, sulfuric acid/hydrogen peroxide solution, and hydrofluoric acid. Publication (3) discloses a wet etching technique that uses, in turn, a buffer ammonium fluoride solution, sulfuric acid/hydrogen peroxide solution, hydrofluoric acid, and pure water.
As described above, conventionally, respective materials to be etched such as organic materials, silicon-type materials, and oxide films or for respective, various kinds of substances to be removed are separately removed by using respective liquid chemicals. Therefore, many kinds of liquid chemicals are used in large quantities. Because of a multibath process in which a substrate is sequentially immersed in different liquid chemicals, the number of steps is large and the processing time is long. Further, it is necessary to switch, many times, between vacuum equipment for dry etching and chemical equipment for wet etching, which complicates the manufacture and quality management.
Further, conventionally, there is no proper method for removing only various kinds of reaction products while leaving a resist mask to use it in later steps or simultaneously removing various kinds of reaction products and a resist mask by a single liquid chemical or a single wet etching step. It is now desired to develop such a method.